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The national average for U.S. on-highway diesel fell 1.4 cents this week to $3.380 per gallon, which marks the first price drop in a month. Last week's $3.494 per gallon U.S. average is the highest average price of the year. This week's national diesel average is 58.3 cents more than it was a year ago.

For the ninth week in a row, every region of the U.S. has an average on-highway diesel price of more than $3 per gallon – ranging from $3.152 on the Gulf Coast to $3.871 on the West Coast. Every U.S. region but the New England and the Rocky Mountains saw decreases in diesel prices this past week. The biggest diesel price decrease was in Gulf Coast (down 2.0 cents). California, which saw a 1.3 cent decrease, still boasts the most expensive diesel per gallon at $4.096.

For the second week in a row, gasoline prices at the pump fell everywhere but on the West Coast. The national average is down 3.8 cents to $2.841 – that's 12.1 cents less than 2018's national high average price of $2.962 per gallon on Memorial Day. This week's national gasoline average price is 36.2 cents more than it was this week in 2017.

Every region in the U.S. except the West Coast saw its gasoline pump prices decrease this past week. The biggest dip was in the Midwest, where prices fell 6.9 cents (after a 6.4 drop the week before) to $2.689. The West Coast ($3.499) is the only region with gasoline averaging more than $3 per gallon.

Here is a look at the week-over-week on-highway diesel prices in every region of the U.S., as EIA reported on Monday night:

East Coast: $3.369 (down 1.3¢)

New England: $3.368 (up 0.7¢)

Central Atlantic: $3.533 (down 1.1¢)

Lower Atlantic: $3.254 (down 1.8¢)

Midwest: $3.333 (down 1.8¢)

Gulf Coast: $3.152 (down 2.0¢)

Rocky Mountain: $3.408 (up 0.8¢)

West Coast: $3.871 (up 0.9¢)

West Coast less California: $3.587 (down 0.4¢)

California: $4.096 (down 1.3¢)

Here's a look at gasoline prices per gallon by region and how they changed this week: